Abstract:
Mite communities inhabiting plants are known to be affected by several environmental
factors, including temperature and humidity. This pilot study aimed to assess seasonal variation in
mite abundance and species richness in three Southern African woody species: Gardenia thunbergia,
Rothmannia globosa (both Rubiaceae), and Tecomaria capensis (Bignoniaceae). Furthermore, we inves-
tigated the influence of rainfall, maximum and minimum temperature, and relative humidity on
mite abundance and species richness. The study was conducted in 2014–2015 in Makhanda, formerly
known as Grahamstown, in the Eastern Cape, South Africa. Twenty mature leaves were collected
from all aspects of the plant fortnightly over 34 weeks. Following sampling, the leaves were viewed
under a dissecting microscope, and mites were collected from inside the domatia and surrounding
leaf surface area. Species diversity and abundance were calculated for each season and compared. A
multiple linear regression analysis was performed in R Studio to test relationships between species
richness and abundance, minimum and maximum daily temperatures, relative humidity, rainfall the
day before, and accumulative rainfall over the preceding two-week period. We found that mites were
present in the leaves of the sampled plants across all seasons, but that mite abundance and species
richness changed with each season. None of the environmental variables were correlated with mite
abundance, and only relative humidity influenced species richness. These results were not consistent
across the three plant species studied, and we point to weaknesses in our sampling approach for the
observed results. This pilot study, one of the first from southern Africa, provides a window into the
complex interactions between plants and mites. We advocate for more studies on mite seasonality to
better understand if it is specific to a region, vegetation type, or host species.
